2005 Ford F150 4.2L Engine P0174 Code: Symptoms, Diagnosis & Vacuum Leak Solutions

My 2003 Ford F150 experienced similar symptoms — intermittent hesitation during morning starts, occasional stalling, and a noticeable drop in performance. I tried multiple fixes including cleaning the MAF sensor, replacing the crankshaft position sensor, and other common repairs. It ended up costing me nearly as much as a professional shop repair. I took it to a mechanic because I started suspecting transmission issues (like slipping), but they diagnosed it as a faulty MAF sensor — replaced for $185 total. I'm now waiting to see if that resolves all the performance problems.

For my truck, code P0174 was linked to the front oxygen sensor on the driver's side. This helped me understand how O2 sensor issues can mimic vacuum-related symptoms even without a check engine light. It’s worth checking if your vehicle has similar sensor or fuel trim behavior.